Collapsible boiler-plug.



W. D. SHONEFELT'& R. VAUGHAN. GOLLAPSIBLE BOILER PLUG.

APPLICATION FILED APR.20,1909.

. 4 927,688; Patented July 13,1909.

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WITNESSES l VENTORS ya/MwfWw/wm W I/I/%/6T M e JO my.

WILLIAM D. SHONEFELT AND RICHARD VAUGHAN, OF SACRAMENTO, CALIFORNIA.

COLLAPSIBLE BOILER-PLUG.

no. ceases.

Specification of Letters Patent.

Patented July 13, 1909.

Application filed April 20, 1909. Serial No. 491,175. A

To all 207mm it may concern:

lie i t kn own that we, WILLIAM D. SHONE- FELT and .lienARn VAUGHAN, both of Sacramento, in the county of Sacramento and State of lalifornia, have jointly invented a certain new and useful Improvement in'( ollapsiblc B(.lll(3l'PlLlgS, of which improvement the following is aspccification.

Our invention relates to means for pre venting the burning or explosion of locomotive and other steam boilers, which frequently results from failure to maintain the proper water level above the crown. sheets thereof and the consequent overheating of the crown sheets.

The object of our invention is to provide an appliancecf such character which shall be simple and inexpensive in its construction; of ready applicability in steam boilers having water wall inclosed fireboxes of any of the ordinary forms; and positive, sensitive, and reliable in operation, by reason of the ab some of any parts requiring shearing strain for their separation or so disposed as to reseal after separation.

The improvement claimed is hereinafter fully set forth.

ln the accompanying drawing: Figure 1 is a plan or topview of a collapsible boiler plug embodying our invention; and; Fig. 2, vertical central section through the same, fixed in operative position in the crown sheet of a steam boiler.

In the practice of our invention, we provide a collapsible boiler plug comprising the followiir members, viz: First, a hollow or tubular body, 1, of metal, as iron or steel, which is open at its lower end and closed at its upper end, except as to a central 0 )ening, 1 and is provided with an external screw thread, 1 throughout a portion of its length, by which it is connected to 'a corresponding internal screw thread, tapped in a hole which is drilled in the crown sheet, 4, of a locomotive or other steam boiler, to receive the plu Second, a disk or late, 2, usually made of brass, which is of slightly less diameter than the bore of the body, 1, and is located therein adjacent to its top. The disk, 2, closes the opening in the top of the body, and is preferably, as shown, provided with a central boss or projection, 2 on its top, fitting neatly in said 0 ening and extending a sufiicient distance to e substantially flush with the upper surface of the top of the body, so as to prevent said opening from becoming choked by deposits of scale. Third, a seal, 6, of tin or other metal fusible at a comparatively low temperature, which. is interposed between the inner surface of the top of the body and the top of the disk, 2, and serves to connect said parts by being fused thereto. The seal being entirely separated from the space above the crmvn sheet, is exempt from liability to become. corroded and is also protected from the direct action of the heat in the firebox, without which protection the fusing properties of the plug would be so impaired as to destroy its reliability in time of need. A characteristic feature of the seal is that it is not connected to the body and disk by screw threads or other interlocking projections, and consequently does not involve the exertion of shearing strain in its separation therefrom. We therefore designate it as plane surfaced, meaning thereby that its surfaces are without interlocking projections. It will, however, be obvious to those skilled. in the art, that so long as the seal is not interlocked with the adj oining members, the specific form of its surfaces, i. a, whether the same are port-ions of flat or of curved planes, is not of the essence of our invention. In the normal operation of the boiler, that is to say, when the water level therein is maintained .at a proper height above the crown sheet, 4, the seal, 3, is protected, by the comparatively cool water surrounding the body of the )lug, from being fused by the heat in the firebox, as well'as protected by being set at a higher level than the crown sheet, at the top of the space within the body of the plug, which acts in the manner of a cooling chamber. hen the level of the water is allowed, by inadvertence or by failure of the feed mechanism, to fall below the nor mal and safe height above the crown sheet, 4, the heat in the firebox will soften and partially fuse the seal, 3, and the plug will collapse, its disk, 2, being separated from its connection with the body, 1, without the pos-' sibility of becoming rescaled, andblown into the firebox by the pressure of the steam above it. .The escape of steam through the opening, 1 ,.in the top of the plug, will give warning to the engineer, and dampen or extinguish the fire, thereby preventing the burning of the sheets or the explosion of the boiler which would. otherwise be liable to result.

We claim as our invention and desire to secure by Letters Patent:

1. In a collapsible plug for steam boiler and the top of the body without interlock sheets, the combination of a hollow or tubular body, having an open lower end and an opening in its upper end, a disk or plate lor'ated within the tubular body, in position to close the upper opening thereof, and a plane sur-. faced seal formed of metal l'usible at coinparatively low temperature, and interposed between and connecting the disk or plate and the top of the body.

2. In a collapsible plug for. steam boiler sheets, the combination of a hollow or tubular body having an open lower end and an opening in its upper end, a disk or plate located within the tubular body, in position to-close the upper opening thereof, and a flat plane surfaced seal formed of metal fusible at comparatively low temperature, and interposed etween and connecting the disk or plate ing engagement with either.

3. In a collapsible plug for steam boiler sheets, the combination of a hollow or tubular ,body having an open lower end and an openin in its u er end a disk 01' )late located within the tubular body and having a boss or 4 projection on its top fitting in andclosing the upper opening of the body, and a seal, formed of metal fusible at comparatively low tern-f perature, and interposedbetween and co n necting the disk or plate and the top of the bpdy, around the projection of the disk 01' ate.

P WILLIAM D. SHONEFELT.

RICHARD VAUGHAN, Witnesses H. TEnNYsoN,

J. SJQUDIN. 

